Tidal High Res (MQA) news...

[miguelito]

Actually, it's pretty prosaic stuff, as Miska pointed out. Many filtering algorithms used to record CDs concentrate on eliminating aliasing, so they ring. The MQA algorithm includes an apodizing (Latin, "remove the foot") filter, which stops a good part of the ringing. So yep, the ringing is indisputably a recording chain error, and yep, an apodizing filter indisputably does fix it.

Hey Jud! Happy New Year - I had a great Festivus.

 

Can you point me to Miska's discussion please?

[miguelito]

A lot of filters can make a substantial improvement. One type that comes to mind is room correction. Depending on personal preference, a gentle equaliser can also have a pleasing effect. That doesn't necessarily make the better-sounding version more correct.

Trudat (will I ever stop saying that? no).

 

Once both hardware and content become more readily available, someone will hopefully do some proper measurements on it. Until then, I'll be treating secretive demos as though they are rigged in some way. Not saying that they are, but they might as well be (and rigged demos are hardly uncommon in general).

Yeah, it's not like the material was of my choice, or anyone's choice. The fact that the 2L guy is supportive sounds to me like maybe this is indeed useful.

[mansr]

The fact that the 2L guy is supportive sounds to me like maybe this is indeed useful.

 

Or the 2L guy simply likes the effect.

[jeffmudrick]

Or the 2L guy simply likes the effect.

 

Given he recorded them himself this carries a bit of weight.

[Jud]

Hey Jud! Happy New Year - I had a great Festivus.

 

Can you point me to Miska's discussion please?

 

For the rest of us! Airing of grievances! Feats of strength!....

 

Re Miska's discussion, looks like you found it in the other MQA thread.

[Jud]

Or the 2L guy simply likes the effect.

 

Since no filter's perfect, pretty much all digital audio can be viewed as an example of one or another sort of "effect." Morten may like the sound of his stuff with ringing or associated phenomena minimized.

[Axiom05]

Actually, it's pretty prosaic stuff, as Miska pointed out. Many filtering algorithms used to record CDs concentrate on eliminating aliasing, so they ring. The MQA algorithm includes an apodizing (Latin, "remove the foot") filter, which stops a good part of the ringing. So yep, the ringing is indisputably a recording chain error, and yep, an apodizing filter indisputably does fix it.

 

The apodizing filter removes the pre-ringing at the expense of increased post-ringing. It does eliminate aliasing (if that is really a problem). Many people prefer a simple minimum phase filter that minimizes both pre and post ringing at the expense of possible aliasing effects (or even a NOS). For example, the Ayre QB-9DSD includes both a minimum phase filter & an apodizing filter. I think the minimum phase filter sounds much smoother than the apodizing filter. What I don't understand is if recordings are made at 96kHz or higher and use a minimum phase filter, what is the need for an apodizing filter? At high sampling rates, aliasing into the audio band should not be an issue at all and a gentle sloped filter should eliminate pre and post ringing.

[miguelito]

For the rest of us! Airing of grievances! Feats of strength!....

 

Re Miska's discussion, looks like you found it in the other MQA thread.

Yeah... I have a problem with most people here! Not you of course.

[crenca]

"...I am all for better sound and not at all against a high quality lossy compression that improves sound and allows high res streaming. I am pissed off beyond belief by utter deception and bull frankly. When I asked the demoers at Meridian NY technical questions I got contradictory yiberish. That is unacceptable."

 

"...Once both hardware and content become more readily available, someone will hopefully do some proper measurements on it. Until then, I'll be treating secretive demos as though they are rigged in some way. Not saying that they are, but they might as well be (and rigged demos are hardly uncommon in general)."

 

+1 on these comments.

 

Who in everyone's estimation do you trust to do such "proper measurments" and objective demos. Based on the fan-boy-dom over at the major audiophile press sources I take in, I am not sure I trust them to be objective about MQA (they have made no effort so far to be).

[Jud]

The apodizing filter removes the pre-ringing at the expense of increased post-ringing. It does eliminate aliasing (if that is really a problem). Many people prefer a simple minimum phase filter that minimizes both pre and post ringing at the expense of possible aliasing effects (or even a NOS). For example, the Ayre QB-9DSD includes both a minimum phase filter & an apodizing filter. I think the minimum phase filter sounds much smoother than the apodizing filter. What I don't understand is if recordings are made at 96kHz or higher and use a minimum phase filter, what is the need for an apodizing filter? At high sampling rates, aliasing into the audio band should not be an issue at all and a gentle sloped filter should eliminate pre and post ringing.

 

You have some things a little turned around. It's minimum phase filters that eliminate pre-ringing while adding to post-ringing, and apodizing filters that can potentially minimize both.

 

96khz is not really a lot of headroom with which to get a gentle enough slope to minimize ringing while not allowing aliasing. That's why 352.8/384kHz very quickly became the standard for CD players and DACs to work from internally. DACs today and Miska's software deal in MHz sampling rates, and PeterSt's software uses 705.6/768 rates.

[tallica1]

The underlying truth about Meridian's MQA which nobody will actually publicly disclose at this time is that this technology was exclusively made for streaming and is perfect for "mainstream" hi-res "STREAMING" and 100% Apple Inc. will soon announce this "no brainer" streaming as the next gen. But in reality DSD 128 is far superior to MQA. THIS IS A GUARANTEE.

[crenca]

You have some things a little turned around. It's minimum phase filters that eliminate pre-ringing while adding to post-ringing, and apodizing filters that can potentially minimize both.

 

96khz is not really a lot of headroom with which to get a gentle enough slope to minimize ringing while not allowing aliasing. That's why 352.8/384kHz very quickly became the standard for CD players and DACs to work from internally. DACs today and Miska's software deal in MHz sampling rates, and PeterSt's software uses 705.6/768 rates.

 

What is the favored "audio digital filters explained in 2000 words or less" link?

[DanSmedra]

Yes, this is the way I read it also.

 

Let's not overlook Doak's solution..."ear enhancements."

[Jud]

What is the favored "audio digital filters explained in 2000 words or less" link?

 

I think http://www.resonessencelabs.com/digital-filters/ does a nice job.

[fritzg]

Since no filter's perfect, pretty much all digital audio can be viewed as an example of one or another sort of "effect." Morten may like the sound of his stuff with ringing or associated phenomena minimized.

 

This is what I've been saying for a while on here, but folks usually come back with something like, "but Miska's filters are superior and don't change the music like other filters do.'

 

Glad to see you're coming around, Jud. ;-)

[firedog]

This is what I've been saying for a while on here, but folks usually come back with something like, "but Miska's filters are superior and don't change the music like other filters do.'

 

Glad to see you're coming around, Jud. ;-)

 

You misinterpret what most users say about HQP. We understand that all filters change the sound of the result and think using HQP does give a

" better" solution, or one we like better. From your other posts, you seem to somehow think that this is essentially different from what ALL D to A or A to D conversion does anyway. Miska's software is not some "violation" of bit perfect reproduction - it is a different, but analogous process to what goes on inside your equipment anyway.

[mansr]

"...I am all for better sound and not at all against a high quality lossy compression that improves sound and allows high res streaming. I am pissed off beyond belief by utter deception and bull frankly. When I asked the demoers at Meridian NY technical questions I got contradictory yiberish. That is unacceptable."

 

"...Once both hardware and content become more readily available, someone will hopefully do some proper measurements on it. Until then, I'll be treating secretive demos as though they are rigged in some way. Not saying that they are, but they might as well be (and rigged demos are hardly uncommon in general)."

 

+1 on these comments.

 

Who in everyone's estimation do you trust to do such "proper measurments" and objective demos. Based on the fan-boy-dom over at the major audiophile press sources I take in, I am not sure I trust them to be objective about MQA (they have made no effort so far to be).

 

Anyone who has the right equipment and is willing to explain their procedure in sufficient detail that someone else with similar equipment might reproduce it. I've found that those who fudge the results tend to gloss over the explanation part.

[Axiom05]

You have some things a little turned around. It's minimum phase filters that eliminate pre-ringing while adding to post-ringing, and apodizing filters that can potentially minimize both.

 

96khz is not really a lot of headroom with which to get a gentle enough slope to minimize ringing while not allowing aliasing. That's why 352.8/384kHz very quickly became the standard for CD players and DACs to work from internally. DACs today and Miska's software deal in MHz sampling rates, and PeterSt's software uses 705.6/768 rates.

 

This link shows the characteristics of the Meridian apodizing filter. This is a true apodizing filter as published by Peter Craven. IIRC Resonessence's description of an apodizing filter is somewhat different and doesn't actually fit the definition as defined by Craven. This is also described in a publication on the Ayre website describing their minimum phase filter.

 

Meridian Audio Prime D/A headphone amplifier Measurements | Stereophile.com

 

https://www.ayre.com/pdf/Ayre_MP_White_Paper.pdf

[monteverdi]

MQA is an enigma for me: what is based on scientific facts and what is marketing?

Some statements about sensory physiology and music comprehension are quite acceptable: the frequency domain plays a important part only in the frequency of our voice (to differentiate similar voices) but for very low or higher frequency only time domain is essential (environmental clues).

I also accept the pre and post ringing both in AD and DA phase are events which cause an unnatural (i.e. "digital") sound signature.

Meridian was one of the first companies to introduce sigma/delta conversion but subsequently conceived of many generations of filters to ameliorate the problems of that technology. I have not found any good comparison of different AD/DA conversion technologies (including R2R and DSD (single bit) and their influences on time domain. Of course on has to also consider that many parts of our sound reproducing chain is not time coherent anyhow (especially most speakers).

[Jud]

This link shows the characteristics of the Meridian apodizing filter. This is a true apodizing filter as published by Peter Craven. IIRC Resonessence's description of an apodizing filter is somewhat different and doesn't actually fit the definition as defined by Craven. This is also described in a publication on the Ayre website describing their minimum phase filter.

 

Meridian Audio Prime D/A headphone amplifier Measurements | Stereophile.com

 

https://www.ayre.com/pdf/Ayre_MP_White_Paper.pdf

 

You're still confused.

 

For oscilloscope graphs of apodizing and minimum phase filter responses and the differences between the two, see H I F I D U I N O: WM8741 Digital Filters. From that page:

 

Whereas in the past audio engineers have insisted in phase linearity (meaning all frequencies have equal phase or delay), More recent research have shown that a "minimum phase" filter sacrifices some of the phase linearity (adds some phase distortion) for better time response. Specifically, minimum phase filters minimizes the pre-ringing of an impulse response.

 

And the following filter impulse response (minimum phase in blue showing no pre-ringing but increased post-ringing):

 

 

Then from the same page regarding apodizing filters:

 

The use of slow roll-off filters allows some of the higher frequency (beyond the Nyquist frequency) energy to be reflected back into the audio band. This is known as "aliasing" an is a source of distortion. An apodizing filter according to the Wolfson white paper, is one where the filter fully attenuates by Fs/2 (the Nyquist frequency) and thus they start attenuating earlier than Fs/2 often sacrificing flat requency response to 20KHz.

 

Followed by this filter frequency response graph:

 

 

The way the apodizing filter achieves minimization of *both* pre- and post-ringing, in contrast to the behavior of a minimum phase filter alone, which eliminates pre-ringing but actually exacerbates post-ringing, is that beginning the response cut at lower frequency allows a gentler slope. It's the gentle slope that minimizes ringing, both pre- and post-. This is shown in the same article with an impulse response graph of the Ayre filter, which combines a gentle slope with minimum phase, but is not apodizing, i.e., does not fully cut by the Nyquist frequency and therefore allows some aliasing:

 

(Edit: Sorry, the bolded wording above is in error - the Ayre filter does fully cut by Nyquist and is apodizing. However, please note the Ayre white paper's discussion of the fact that it is the gentle slope or "roll-off" of their filter that minimizes both pre- and post-ringing vs. a minimum phase filter alone.)

 

 

Once more, as explained at the same link:

 

"Apodising" ("Apodizing" in American English) filters have been equated to minimum phase filters and minimum phase filters with slow roll-off in the literature. But as the name of the filters in the Wolfson DAC suggests, "apodizing" is an additional filter technique to that provided by minimum phase soft-knee.

(Emphasis added; "soft-knee" = gentle slope.)

[Axiom05]

You're still confused.

 

For oscilloscope graphs of apodizing and minimum phase filter responses and the differences between the two, see H I F I D U I N O: WM8741 Digital Filters. From that page:

 

 

 

And the following filter impulse response (minimum phase in blue showing no pre-ringing but increased post-ringing):

 

[ATTACH=CONFIG]23179[/ATTACH]

 

Then from the same page regarding apodizing filters:

 

 

 

Followed by this filter frequency response graph:

 

[ATTACH=CONFIG]23180[/ATTACH]

 

The way the apodizing filter achieves minimization of *both* pre- and post-ringing, in contrast to the behavior of a minimum phase filter alone, which eliminates pre-ringing but actually exacerbates post-ringing, is that beginning the response cut at lower frequency allows a gentler slope. It's the gentle slope that minimizes ringing, both pre- and post-. This is shown in the same article with an impulse response graph of the Ayre filter, which combines a gentle slope with minimum phase, but is not apodizing, i.e., does not fully cut by the Nyquist frequency and therefore allows some aliasing:

 

(Edit: Sorry, the bolded wording above is in error - the Ayre filter does fully cut by Nyquist and is apodizing. However, please note the Ayre white paper's discussion of the fact that it is the gentle slope or "roll-off" of their filter that minimizes both pre- and post-ringing vs. a minimum phase filter alone.)

 

[ATTACH=CONFIG]23181[/ATTACH]

 

Once more, as explained at the same link:

 

(Emphasis added; "soft-knee" = gentle slope.)

 

I did not write the information in the links that I provided. This is what Meridian is using and calling an apodizing filter. It is taken directly from Peter Craven's AES paper on what he termed an apodizing filter. It is a type of minimum phase filter with specific characteristics as shown in both links provided. Not much more to say on that.

[miguelito]

What is the favored "audio digital filters explained in 2000 words or less" link?

That's called "Miska" and it's a person (I think???).

[jeffmudrick]

The underlying truth about Meridian's MQA which nobody will actually publicly disclose at this time is that this technology was exclusively made for streaming and is perfect for "mainstream" hi-res "STREAMING" and 100% Apple Inc. will soon announce this "no brainer" streaming as the next gen. But in reality DSD 128 is far superior to MQA. THIS IS A GUARANTEE.

 

I'm not sure there is anything conspiratorial going on. The ability to fold a high rez file into a more compact package for streaming is not some hidden feature, it's a primary selling point of the technology and part of every pitch Meridian makes. It's one which I welcome.

[TPiddy]

I'm not sure there is anything conspiratorial going on. The ability to fold a high rez file into a more compact package for streaming is not some hidden feature, it's a primary selling point of the technology and part of every pitch Meridian makes. It's one which I welcome.

 

+1

 

I have a hard time seeing harm in a broader group of services streaming higher bit rate music than they currently offer. If apple chooses to get into the game then it seems to me all boats will rise.

 

I guess the proximity of the "rise of MQA" and North Korea's claim to have detonated a hydrogen bomb is suspicious though.

 

In all seriousness, I am a big streaming fan and own an Aries and a vega (so maybe I am admittedly a homer) and look forward to seeing seeing if the buzz is real at CES tomorrow and Friday.

[crenca]

+1

 

I have a hard time seeing harm in a broader group of services streaming higher bit rate music than they currently offer. If apple chooses to get into the game then it seems to me all boats will rise.

 

 

Truly, this sounds like you took it from the promotional material Meridian is passing out. Is MQA really, truly a "no downside - all upside" achievement for you (a first in the history of human endeavor)? If so, what do you base this conclusion on besides the promotional material and those who repeat it? Do you normally take product marketing at face value? If so, I got some beachfront property in Arizona I wish to discuss with you...it's a great deal...you can watch those boats in the water...

 

It is best to remember that MQA is a consumer audio PRODUCT, nothing more and nothing less.